I'm thinking of buying one of these and fabricating any necessary adapters or fittings to make it work in the Z.
Fluidyne High Performance Universal/Racing Radiators - UltraRev.com
It's over twice as thick as the CSF and costs half as much. Also doesn't come with a useless AC Condenser that I have to pay for.
Edit: And according to the Fluidyne catalog, the inlet and outlet are on the correct sides of the thing, unlike that photo on the website I linked. I'll be calling the company to confirm before ordering, if I decide to move forward with it.